1. Field of the Invention
This invention relates to the field of modeling and data representation, and in particular to the modeling and representation of medical reports, via the use of DICOM SR relational data.
2. Description of Related Art
The Digital Imaging and Communications in Medicine (DICOM) Structured Reporting (SR) standard, and the SR Documentation Model upon which it is based, improves the expressiveness, precision, and comparability of documentation of diagnostic images and waveforms. DICOM SR supports the interchange of expressive compound reports in which the critical features shown by images and waveforms can be denoted unambiguously by the observer, indexed, and retrieved selectively by subsequent reviewers. Findings may be expressed by the observer as text, codes, and numeric measurements, or via location coordinates of specific regions of interest within images or waveforms, or references to comparison images, sound, waveforms, curves, and previous report information. The observational and historical findings recorded by the observer may include any evidence referenced as part of an interpretation procedure. Thus, DICOM SR supports not only the reporting of diagnostic observations, but the capability to document fully the evidence that evoked the observations. This capability provides significant new opportunities for large-scale collection of structured data for clinical research, training, and outcomes assessment as a routine by-product of diagnostic image and waveform interpretation, and facilitates the pooling of structured data for multi-center clinical trials and evaluations.1 
1xe2x80x9cClinical Rationale for the SR Documentation Model and the DICOM Structured Reporting (SR) Standardxe2x80x9d, Abstract, W. Dean Bidgood, Jr., (copyright) 1999. 
The DICOM SR is based on a relational data technology, and has been standardized by the National Electrical Manufacturers Association (NEMA). Supplement 23: Structured Reporting Storage SOP Classes to the DICOM Standard, published by the DICOM Standards Committee, 1300 N. 17th Street, Rosslyn, Va. 22209 USA, and incorporated by reference herein, introduces the SR Service-Object Pair (SOP) Classes for transmission and storage of documents that describe or refer to any number of images or waveforms or to the specific features that they contain. This standard is expected to be adopted by the medical equipment manufacturers and providers at large to provide text, image, and waveform content in a structured reporting format.
Although the DICOM SR standard provides for a consistent reporting and recording scheme, the use of the information contained in a DICOM SR is limited to DICOM compliant applications that can process this information using the DICOM specific format. Application developers must be DICOM literate, and a methodology for deploying applications that interoperate with other applications outside the DICOM domain has not yet been developed.
In the computer industry, progress has been made in the use of standardized languages and methodologies that facilitate the use of information from a variety of sources by a variety of applications. A standard language that is widely used for processing content material is the World Wide Web Consortium Extensible Markup Language (XML), which is derived from the Standard Generalized Markup Language (SGML), and is designed to describe data and its structure so that it can be easily transferred over a network and consistently processed by the receiver. Because XML is used to describe information as well as structure, it is particularly well suited as a data description language. One of XML""s particular strengths is that it allows entire industries, academic disciplines, and professional organizations develop sets of Document Type Definitions (DTDs) and Schemas that can serve to standardize the representation of information within those disciplines. Given a set of DTDs and Schemas, content material that is modeled in conformance with the DTDs and Schemas can be processed by applications that are developed for these DTDs and Schemas.
A further advantage of the use of XML is the wealth of tools that are available for the processing of XML-compatible data. Of particular significance, the xe2x80x9cExtensible Stylesheet Languagexe2x80x9d (XSL) is a language for expressing stylesheets, and the xe2x80x9cXSL Transformationsxe2x80x9d (XSLT) is a language for transforming XML documents into other XML documents, using stylesheets. A stylesheet contains a set of template rules, which are used to match a pattern to a source document, or xe2x80x9csource treexe2x80x9d and, when the appropriate match is found, to instantiate a template to a result document, or xe2x80x9cresult treexe2x80x9d. In this manner, XML information that is structured for one application can be relatively easily transformed into a different structure for another application.
Although XML may be considered a relatively new and specialized language, it can be expected that more programmers and other computer professionals will be familiar with XML than those who are familiar with DICOM. Additionally, it can be expected that more general-purpose utilities and applications will be available for use on XML encoded information than will be available for use on DICOM SR encoded information.
An objective of this invention, therefore, is to provide a method and system that facilitate the creation of XML Document Type Definitions (DTDs) and XML Schemas that correspond to the DICOM SR standard. A further objective of this invention is to provide a method and system for creating an XML representation of DICOM objects that is flexible and extensible.
These objectives and others are achieved by providing a conversion system that converts the DICOM SR standard into a set of XML DTDs and Schemas. By providing a mapping between the DICOM SR standard and XML DTDs and Schemas, DICOM specific XML-based applications can be developed, via a larger field of XML-fluent application developers. Additionally, by providing standard XML DTDs and Schemas for containing DICOM data, other commonly available non-DICOM-related applications, such as accounting and mailing programs, can be structured to use information as required from DICOM reports that are converted to conform to these defined XML DTDs and Schemas. In a preferred embodiment, a two-phase conversion is employed. The DICOM SR specification is parsed and converted directly into a set of xe2x80x9crawxe2x80x9d XML documents. Thereafter, the xe2x80x9crawxe2x80x9d XML documents are transformed into the corresponding XML DTDs and Schemas, via an XSLT processor. Changes to the desired XML DTDs and Schemas, as standards develop, can thus be effected via changes in the corresponding XSLT stylesheets, without modification to the DICOM-to-raw-XML process.